Generally, a variety of vehicles such as passenger cars for drivers or passengers, wheelchairs used for patients or handicapped persons, trucks used for carrying cargos and loads, and special cars such as armored vehicles and specially-equipment vehicles have been developed to enhance convenience and be effectively used for special purposes.
As shown in FIG. 1, a conventional vehicle includes a wheel frame 1 that can be formed in a variety of designs capable of receiving persons or cargos. An engine is mounted on a predetermined location of the wheel frame to generate power. Driving shafts 4 are further installed on the wheel frame 1 to drive wheels 3 by receiving the power from the engine 2. Therefore, when the engine operates, the wheels 3 connected to the driving shafts 4 rotate to drive and move the vehicle.
The conventional vehicle is generally configured such that the wheels perform only the rotating drive with respect to axle shafts or driving shafts. Therefore, on an even road or when an obstacle is less than a predetermined height, the vehicle can easily move. However, when the vehicle meets a sand field, a muddy field, a high obstacle, or stairs, the wheels may not have any traction or may not go over the obstacle, and thus the vehicle cannot be driven or move.